This invention relates to a rappelling device and in particular to such a device which does not have any moving parts and still can be attached to the middle of the line with which it is being used without causing any net twisting of the line.
Many devices are known for slowing the rate at which a person descends a line. In addition, many of these devices are arranged to allow them to be attached to the line at an intermediate point. Such devices are used in recreational activities and rescue work, such as in rock climbing, as well as for commercial endeavors, such as building maintenance and window washing.
The prior art devices of this type have two shortcomings, however, which limit their usefulness. First, such prior art devices are capable of being attached to the line at its center only by having moving parts which allow the devices to be opened to admit the line into them or to clamp onto the line. Not only does this increase the complexity of the device, which increases its cost, it makes it difficult to attach the device to the line since the user must close the movable elements and ensure that they are locked in the closed position before using it. This difficulty in attaching the device to the line increases the likelihood that the device will be dropped when it is being attached, as well as slowing down the attachment process. Furthermore, the existence of moving parts on the device makes the possibility of failure greater, which lessens the confidence of users in it.
Another shortcoming of the prior art rappelling devices is that the line generally is wrapped onto the device in one direction only. Thus the line tends to become twisted which makes it susceptible to damage when shock loading occurs and the line has increased fiber wear due to the torsional stress caused by the twisting.